The present disclosure relates to transparent block copolymers formed from polycarbonate blocks and silicone blocks. These block copolymers have a high elongation before yield and other desirable mechanical properties.
Polycarbonates (PC) are synthetic engineering thermoplastic resins derived from bisphenols and phosgene, or their derivatives. They are linear polyesters of carbonic acid and can be formed from dihydroxy compounds and carbonate diesters, or by ester interchange. Polycarbonates are a useful class of polymers having many desired properties, such as optical clarity, good impact strength, and higher heat distortion temperature (HDT).
Conventional silicone polycarbonate block copolymers have been recognized for their ductility/impact strength at low temperatures and flame retardance. However, said silicone block copolymers have been found to exhibit an undesirable attribute, low transparency and high degrees of haze, which is problematic for some end-uses of the material and limits the nucleus of uses for said resins. It would also be desirable to obtain a silicone polycarbonate block copolymer that exhibits elastomeric behavior, or in other words can be stretched and return to its original shape without permanent deformation coupled with an acceptable transparency.